


Out of Innsmouth (Sort of, Kind of, But Not Really)

by tepidspongebath



Category: Cthulhu Mythos - Fandom, Sherlock (TV)
Genre: Consentacles, Double Penetration, I regret some things this isn't necessarily one of them, Light Bondage, Lots of penetration actually, M/M, PWP, Sounding, Tentacle Sex, Tentacles, This really is quite weird
Language: English
Status: In-Progress
Published: 2013-06-07
Updated: 2017-01-30
Packaged: 2017-12-14 05:10:13
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 8
Words: 7,707
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/833112
Author URL: https://archiveofourown.org/users/tepidspongebath/pseuds/tepidspongebath
Summary: <blockquote class="userstuff">
              <p>John Watson cautiously reveals his family history to Sherlock Holmes, fearing that his unusual heritage will get in the way of their relationship (or, more precisely, the relationship he <i>wants</i> them to have). </p>
<p>It doesn't. It actually, well, helps things along. In quite a multitude of ways.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> Written for [a prompt on the kink meme](http://sherlockbbc-fic.livejournal.com/19743.html?thread=119422751#t119422751) asking for John to have tentacles, and, after a cautious revelation, for him to fuck Sherlock with them. Bonuses were also offered for the inclusion of various very specific details, and will try to hit all of them.
> 
> A slight, slight crossover with the Cthulhu mythos to explain the tentacles away. I, er, seem to have pushed logic out of the window and crippled it. And I fear I may have overdone things (and it's also very long), and am now going to Hell in a fast train. I apologize.

"It's like this." John whistled through his teeth as he looked for a way to explain it. "Mum's from Innsmouth."  
  
Sherlock frowned at the unfamiliar name. He still wasn't sure what this was about. "Innsmouth? I've never heard of it."  
  
"Of course you haven't. Little town by the sea in New England. She was born there. Though maybe I should start with my grandmother."  
  
"Are we sharing family histories now? I ought to have texted Mycroft."  
  
" _Sherlock_. Listen. Please. My grandmother  _wasn't_  from Innsmouth, not originally, but her family moved there when she was a kid. Um. Actually it might be a better idea to start with my grandfather--"  
  
"Also from Innsmouth?"  
  
"No. Definitely not. Though he visited the place. Probably still does."   
  
"He's still alive?"  
  
"You know, I can't even wrap my head around the thought of him being dead. Not that I've met him. Not that I  _want_  to meet him, when it comes to that."   
  
Sherlock let his flatmate have a quiet moment to contemplate his familial difficulties.   
  
"Anyway," John went on eventually, "my grandmother came to Innsmouth, and my grandfather came there every so often, and my Mum and my uncles happened before my grandmother got married to an Englishman."  
  
"Ah."  
  
"He was a very understanding bloke, and my grandmother liked him, but he didn't want her to stay in Innsmouth, and she was pretty glad to get out of there, to be honest."  
  
"I take it she didn't like your grandfather very much?"  
  
"Look, it wasn't - it wasn't your conventional setup, all right? Maybe she liked it at first, maybe she didn't have a choice, and, God, I do not want to think about my grandparents' sex life, if you don't mind."  
  
Sherlock gave him a look to say that he could imagine quite a few non-conventional setups, no need to be queasy around him.  
  
" _Anyway_ , Mum was all right, her first brother was stillborn, Uncle Phil wandered into the sea during a summer holiday at Cornwall and never came back out, and Uncle Henry eventually had to be shut up in a mental institution. He, er, escaped, and we never heard from him again. I've got other uncles who're normal, but they're Mum's half-brothers.  
  
"And then Mum married Dad, and they had Harry, and she was fine. And then they had me. Er." John scratched unconsciously at something at the small of his back. "I'm a bit of a throwback to my granddad."  
  
"I don't see any problem there."  
  
"Well, I've kept it under wraps, haven't I? I've gotten good at keeping it secret. Mum knows, of course, Dad knows though he was floored by it, and sometimes I wonder if knowing drove Harry to drink. I used to enjoy giving her a scare before I knew any better. She still can't stand the sight of an octopus." John's face took on a thoughtful look. "And some of my old girlfriends know. And old boyfriends."  
  
Sherlock made an impatient noise. "And the point of all this is?"  
  
"Granddad…he wasn't a person."  
  
"Oh, for God's sake!"

"Seriously, Sherlock, he wasn't human. Sometimes I wonder if he's even a 'he', they don't have nice and orderly sexes like we do. Like you do, I mean." John took a deep breath. "My grandfather was one of the Deep Ones."  
  
"The Deep Ones?"  
  
"The Deep Ones, the Old Ones, the  _Great_  Old Ones, if you're so inclined. They're not from" - John waved a hand around vaguely, as if trying to indicate the entire world, no, the entire  _universe_  - "here. I don't rightly understand it all myself, and I don't actually  _want_  to understand it, but given the state of things, I've had to try and figure it out. Just a little. Just enough.   
  
"I'm not even sure which one Granddad was. All I know for certain is that it wasn't one of the major ones, Dagon and so on. I  _think_  he was at least some part human himself, which is why it worked out so well for my Mum and Harry. They're just carriers, you see. They get off okay. But it's a little different for the men in the family." His mouth twisted in a grimace. "Thanks to Dad being completely normal, I don't have it as bad as, say, Uncle Henry. But I do have a set of tentacles."  
  
It was a mark of Sherlock's great self-control that all he did at this was revelation was blink, twice. "What?"  
  
"You heard me. I've got tentacles, a set of them. I can't tell you exactly how many, that changes. The Deep Ones, well, they basically tell the laws of physiology and physics and logic in this universe to go and fuck it, and the bit I inherited from them does that too." John's face darkened. "I've tried to get rid of them - why do you think I became a doctor? - but nothing's worked."  
  
The consulting detective looked his flatmate up and down with that weighing, measuring, calculating look of his. "You're pulling my leg," he said finally.  
  
"What do you think I am, nine years old with an overactive imagination?" John demanded indignantly. Sherlock was about to point out  _exactly_  why it couldn't possibly be true when the doctor pulled up the hem of his jumper and a long, twisty  _something_  snaked out from under it, looped around Sherlock's ankle and gave it a light tug. " _Now_  I'm pulling your leg."  
  
For once Sherlock was utterly speechless. He watched openmouthed as John removed the  _thing_  - yes, it was a tentacle, wasn't it? - from around his leg and slid it docilely back beneath his clothes. "Why are you telling me this?" he asked quietly, after a rather uncomfortably long silence.  
  
"Because you're my friend. And I live with you." John had rearranged his jumper and was looking at him with that defiant jut of his chin that he got whenever he was about to face anything particularly challenging. "AndIfancyyouallrightitdidn'tseemfairtosaysoifyoudidn'tknow."

"Ah." It was the wrong thing to say to something like that, and Sherlock knew it the moment John's face took on a rigid, set expression. This wasn't an area that he was comfortable with, that he didn't usually care about, actually, only in this instance he did care very much, but he didn't know how to go about it. Saying  _I fancy you too actually_  would be honest but anticlimactic and Sherlock could quite bring himself to say the words, not after months of _not_ saying them, and  _I don't mind your extra appendages_ wouldn't be quite true - the fact was too new, he didn't know how it computed yet. An observation, though, that would be safe. "That's why your old girlfriends knew."  
  
"And boyfriends," John reminded him, matter-of-factly. He was less wired now that he'd got it all out. "I think I might have gotten that from Granddad too. Er. Sexuality, I mean. Lack of boundaries regarding it, more like. They're really not anything like humans at all, Granddad's people."  
  
"So I gather."  
  
John licked his lips. "There's no hiding it when the clothes come off, you see. So I either have to come clean or come up with a very clever explanation as to why the sex has to happen with me fully dressed except for the important bits." He smiled wryly. "They do make for a pretty interesting sex life though, once the secret's out of the way. Not," he added, "that it matters."  _Since you're not _interested_  _went unsaid. "But at least you won't be running for an exorcist or the like if you walk in on me in the bath." And he gave his flatmate what was meant to be a hearty grin before walking to the stairs that led to his bedroom.  
  
"Wait," said Sherlock. He pressed his lips together in a hard line before going on. "It does matter."  
  
"Sorry?" The doctor stopped in his tracks, turned around to face his flatmate. He sounded like he hardly dared to believe what he was hearing.  
  
"It. Does. Matter." Sherlock went over to John, put a hand on his arm in a gesture that became surprisingly intimate. "I believe you said 'interesting'?"  
  
And that was as close to a confession of undying love (with great and liberal amounts of prospective sex) as he was about to get.


	2. Chapter 2

Sherlock had, of course, wanted to see them. They'd gone upstairs for it, to John's room, partly because Sherlock could tell that he'd be more comfortable about it there, and partly because the light was better in that part of the flat at this time of day.  
  
"I want to see you too," said John, half-jokingly, as he started to pull his jumper over his head (he was wearing a button-down shirt beneath that, and was still showing hardly any skin at all).  
  
"All right." Sherlock stood from where he'd been sitting on the bed, and started, without any apparent compunction, to undress. He'd discarded his shoes, shrugged off his jacket and his shirt, and was starting to work on unfastening his trousers when John, frozen by the spectacle, found his voice again.  
  
"You don't actually have to do that."  
  
"Do you want me to stop?" The consulting detective straightened up, one hand on his partly undone belt.   
  
"No, no, not at all. Just. You don't have to."   
  
"I want to. Fair trade." And Sherlock pulled his belt loose, and started to undo his fly.  
  
"Not quite. I know what a human body looks like, Sherlock. It's no great mystery to me."  
  
"You haven't seen mine," said the detective simply.  
  
John grinned in spite of himself, and set to unbuttoning his shirt. "Fair point." He made a small, throaty noise when his flatmate, already down to his pants, hooked his thumbs on the elastic waistband and pulled the cotton briefs downward.  
  
"Exactly." Sherlock's lips curved in a slow, satisfied smile. He stepped out of his pants, shaking them off of his ankle, and approached John, standing just out of reach. "Now you. Go on."  
  
John's fingers shook as he took the rest of his clothes off: shirt, undershirt, shoes, socks, jeans and boxers. They stood like that for quite a while, in the buff, regarding each other carefully. (John licked his lips more than once. Sherlock just stood there and breathed.)  
  
"I don't see anything very different," Sherlock said at last.  
  
"Not from the front."  
  
Sherlock nodded. He began to pace then, slowly and deliberately, around his flatmate, who stood as still as he could in the middle of the open space between the bed and the wall. When he saw them, he had to stop and close his eyes. It wasn't that they were hideous or repellent (and they'd have to be  _extremely_  hideous or repellent to put off a man who kept samples of ground up human liver next to the bottle of actual liver pate in the fridge), but they were  _wrong_. No, Sherlock thought, opening his eyes again, and squinting at them.  _Wrong_  wasn't the word he wanted. They didn't belong, they didn't fit, it was like trying to make a three-dimensional image fit a two-dimensional point of view, (and that just might have been the actual case, only with much more dimensions) and it made his head swim to look at them for long.  
  
It didn't help that they didn’t really stop moving now that they were exposed.  
  
John cleared his throat. "I wouldn't look too long if I were you. Even I get queasy watching them."  
  
And Sherlock padded closer, squeezed his eyes shut, and touched them. "What does it feel like?" he asked, as the tentacles undulated beneath his hand, felt up his arm.   
  
"Well." John looked over his shoulder. "Sort of normal, I guess. I haven't ever been any other way."  
  
"No, I mean, how does this feel  _here_." Sherlock pressed just a little harder. "My hand there. What does it feel like?"  
  
"Ah." The doctor shrugged. "I can feel it's there, I know I'm touching it" - a small tendril dragged along Sherlock's index finger to prove the point - "but that's about it. I don't know. They don't actually feel very much. A different kind of nervous system is my guess, but that's a complete shot in the dark."  
  
"Mhm." Sherlock withdrew his hand (one of the tentacles uncurled from his arm gently as he did), and circled his flatmate till they were facing each other again. It was a much more comfortable view. "So how do we start?"


	3. Chapter 3

"What?" The doctor looked non-plussed as he started to reach for his discarded underwear.  
  
"You said 'interesting,' and here I am." Sherlock moved closer, his eyes flicking downward to look at John's apparently normal cock and balls. "Or does it work differently for you?"  
  
"It - it works the same, actually. I just didn't think - " He broke off, startled by Sherlock's proximity. That the man had complete and utter disregard for personal space became more of a problem when both of you were starkers. " _Now_?"  
  
"Yes, now. We're both naked, I'm appallingly interested, you'd be lying if you said you weren't, and getting dressed again to go downstairs and watch telly would be a shameful waste of the afternoon." And he kissed John, a long, lingering, maddeningly  _gentle_  kiss on the mouth.   
  
"All right," said John, spots of color forming high on his cheeks. "I'm up for it."  
  
"Good." It might not have been the most enticing invitation to sex - truth to tell, it might be construed as downright clinical -  and the acceptance thereof was smilarly matter-of-fact, but the kiss was deeper this time, and hungrier. "I want all of you, John," murmured Sherlock, 

"Same here." John licked a wet stripe down Sherlock's jawline, started to suck and nip at his neck.  "God, yes."  
  
" _All_  of you," repeated Sherlock, and he had to stop to give a little groan when John, who had inched downwards, took his nipple between his teeth. "In as many ways as you can give it to me."   
  
"Wait." The doctor pulled away (the sudden loss of contact made Sherlock draw a tight breath), straightened, squared his shoulders. It evidently took him some effort to restrain himself. "You've done this before, haven't you?"  
  
"Had sex with a man with tentacles? Not to my knowledge, no."  
  
"But you have had sex."  
  
"I know how it works."  
  
" _Sherlock_." John took a step backward, crossed his arms over his chest, with his other appendages as withdrawn as he could make them. He didn’t have to say that he didn't want to risk hurting Sherlock, to chance damaging him; it was all in the crinkle of his eyes and the stubborn set of his expressive mouth.   
  
"Yes, all right, I have." Sherlock's tone was petulant. "Enough to know what I like."  
  
The wording was distressingly familiar. "Irene Adler?"  
  
"Yes, if you must know."  
  
John started to ask  _how_ , but thought better of it.  
  
"A very inventive woman, Miss Adler."  
  
"Yeah, I remember."  
  
"So you can be as creative as you like. I know what I'm asking. Do whatever you like, whatever you can. That's what I want from you." Sherlock smirked. "It would be a shame to let your heritage go to waste."  
  
"Oh, I haven't let it, trust me. I know how to have me a  _good_  wank." There was unparalleled mischief in John's grin. But he turned serious disappointingly fast. "I'll take you at your word, but you will let me know if it's too much for you?"   
  
It wasn't really a question. Sherlock nodded (though, in truth, he would have agreed to anything at this point), and John, satisfied, moved in to begin.

**Notes for the Chapter:**

> Er, I believe I _did_ say that I pushed logic out the window?


	4. Chapter 4

It started simply enough, or as simply as it possibly could given the situation. They kissed and they touched, standing there in the open space of John's room, exploring and teasing and caressing, only for every touch Sherlock made (his hand light against the sunburst of a scar on John's left shoulder, his fingers in the hair at the back of John's head, the tip of his tongue darting into John's navel), John answered with a dozen, two dozen more. The tentacles were maddeningly fluid, and Sherlock couldn't tell if there were just a few of them that changed or split apart or fused in an indecipherable array, or if there really were that many, of that many weights and thicknesses. Tips of the things ran over his eyelids and cheekbones, made him shiver as they trailed down the sensitive skin at the back of his neck. More substantial appendages looped round his waist to rest just above the curve of his buttocks, around his neck so that the tip could tickle him behind the ear, and another went higher and higher up the inside of his thigh, until he had to gasp harshly into John's mouth at the sensation.  
  
"You all right?" John asked. His hands had been on Sherlock's chest, finger and thumb teasing his nipples into hard dark peaks, and he stopped that as Sherlock shuddered deliciously against him.   
  
"Yes. Yes, I'm fine." And he was. For all that they were incredibly alien, the tentacles were covered in flesh, or something very much like it, and their warm touch was not unpleasant, even if some of the tips were slick with what might have been some sort of natural oil. Sherlock rather liked it, in fact.   
  
"Can I try something?" John slid a hand down to Sherlock's arse, uncurled the tentacle that had been resting there.  
  
"What did I tell you?" Sherlock bit down on John's lower lip to show exactly what he thought of his caution.   
  
John made a noise that might have been satisfaction or annoyance or a bit of both as he sucked on his lip (Sherlock had broken skin). Tendrils began to snake their way to his flatmate's arse to join his hands, cupping the cheeks, squeezing them, running down the cleft, over the tight, puckered entrance. Words and half-formed sounds caught in Sherlock's throat as tentacles parted his cheeks (aided by others that were pulling his feet apart and still others that were helping him keep his balance), and one, very slim, poked delicately at his anal sphincter.  
  
His knuckles went white as his grip on John's shoulders tightened when the thing slipped inside.  
  
"Still all right?"  
  
"I'm fine. I'm not made of porcelain, you won't break me." Sherlock did have some trouble getting the words out, though. The thing was wriggling around, opening him wider. "You?" He'd noticed that John's cock was still lying flaccid against the side of his leg.

John looked down, grinned ruefully. "It takes a bit to get me going."  
  
The tentacle in Sherlock's arse withdrew, and he whimpered a little at the sudden emptiness, and the cold rush of air. It didn't last for long, though, and a thicker tendril (or was it the same one, only fatter?) plunged roughly into the stretched hole. It pulsed once, twice, pulled out again, and thrust back inside,  _deep_  inside before settling into an unsteady rhythm, sometimes brushing against Sherlock's prostate, sometimes missing entirely.  
  
"This still isn't a bit?" panted Sherlock. It wasn't the best he'd been fucked, but it was the entire situation that had his prick erect and leaking precome against his stomach. His hands were on John's shoulders, John was holding him up, and he still wasn't hard.  
  
John kissed his forehead apologetically (Sherlock being bent just low enough for him to do that). "I told you, they're not sensitive, not like that." He paused as Sherlock gave a cry at a particularly hard thrust, and softly touched a tendril to the other man's cheek. "But I could watch you all day, like this. God, you're lovely." John sent a tentacle to lift his flatmate's chin up. 

"I could - do something - about that," Sherlock offered, nodding vaguely in the direciton of John's groin. 

"Ah." The doctor's anticipation could be read in the tautness of his voice, the slight hitch in his breath. "Something you've done before, then?"

Sherlock shook his head. He was shaking now. The thing fucking him from behind was getting better at aiming. "First time for everything. Let me get to my knees."


	5. Chapter 5

The tentacles guided him down when John let him go (let go with his hands, to be more precise), tugging at his arms and legs while the one in his arse just  _went on_. His mouth opened slackly, he grabbed at John's hips for support, and he took the very tip of John's cock between his lips - instinctively, because it was there, it was  _right there_. He gave it a soft suck, doing his best to avoid using teeth (he knew the _theory_ _)_ , touched his tongue to the underside of the head, _tasting,_ and he felt John twitch, swell ever so slightly in his mouth, when a thought suddenly occured to him.    
  
He pulled away, sat back (the tentacles let him - even the one fucking him let up for a bit), answered John's questioning look with a challenging one. It wasn't good of him, and he knew it, but he said it anyway. "You said you knew how to have yourself a good wank."   
  
John passed a hand over his eyes as if he could tell where this was going. "Oh, nameless dreads," he said.  
  
"Show me."  
  
The doctor looked uncomfortable, and the tentacle in Sherlock's arse stopped entirely.   
  
Sherlock put a hand on his own prick, rubbed a thumb over the glans. He tilted his head back, moaned a little for effect. The upward cant of his hips was, however, entirely involuntary. "I could just get myself off, and walk away."  
  
"And I could get myself off when you're gone."  
  
"But you're not going to, are you?"  
  
"Of course you're right about that. Damn you." The invective lacked venom though, and John exhaled steadily, readying himself. He took the tentacles, all of them, away from Sherlock (the detective slumped, ending with his back slouched and his arse - slightly sore - resting on his heels), and, as if an afterthought, looped the coils of one around Sherlock's wrists, holding his hands firmly away from his cock. "But you're not touching yourself till I'm done, okay?"  
  
His flatmate nodded in curt acquiescence.    
  
"Right." John moved backward, took himself in hand. He began to pump his shaft with firm, even strokes, sometimes working the foreskin to the head of his penis and then as far back as it would go, sometimes running a thumb provocatively over the slit. If getting himself erect was the entire point of it, he was managing it magnificently, but it was, so far, a pretty ordinary hand job. Sherlock said as much.  
  
"Be patient," grunted John. His chest was heaving with his deeper breaths, and an dark flush was starting to spread up his cheeks and down his chest.   
  
"You know I rarely am." Sherlock flexed his fingers, willing himself not to strain against John's tentacle. He was a muddled mess of hormones now, he knew that much, and somehow the restraints at his wrists highlighted the fact that he needed, desperately, to do  _something_ , so much so that he was almost beginning to regret not sucking John off.

John's answer to that was barely syllabic. He slid to his knees in front of Sherlock, angled slightly sideways so that the curve of his arse was visible while saving the other man the full, eye-wrenching view of his tentacles. A small jolt went though Sherlock when he realized that it was a rather practiced move, that John had, in all probability, done something like this before with someone else. The thought was distracting and he almost missed when the first tentacle came into play.

It slithered forward between John's legs, and for a brief moment it gave the obscene impression that John had sprouted another dick. Then it curved back, the tip giving John's cock just the lightest of touches before it caught his balls in a curl of its tip. Sherlock could see when it tightened, and the way John squeezed his eyes shut and groaned throatily gave him a shrewd idea of what that must have felt like.

Another two tentacles snaked around his waist, up his ribs, and up to his nipples. They pinched and pulled at the little nubs, and John's hand went to one of them, fingers curling around the fleshy coil, pushing it harder against his skin. His other hand was still on his cock, but his strokes were uneven and increasingly artless.

John turned his neck to look at Sherlock, pupils blown wide in eyes that were fixed on his flatmate.  _Look what you're making me do,_  he seemed to be saying (Sherlock was familiar with that look, though in vastly less erotic situations). 

A fourth tentacle peeled away from the mass of them behind John then, thick and blunt-tipped, and it shone dully as if moist. It traced the cleft of his arse, and Sherlock saw it stop when it reached his sphincter. He could guess at what would happen next, and it became truly obvious when the thing kept nudging at John's entrance, circling and dragging back and forth across it. But he let out a surprised cry (drowned out by John's much louder, much less surprised one) when it plunged into John with barely any preparation, and proceeded to fuck him thoroughly. 

It was a while before Sherlock realized that he was matching the frankly pornographic sounds John tumbling out of John's mouth. The sight was making him  _ache_  , his cock throbbing hot and hard against his belly, but the coils holding his hands together didn't even loosen their grip despite all that was going on at their other end. Things only got worse when it dawned on him that he'd been automatically thinking of the tentacles as a separate element, as if they were another entity entirely, but that was wrong, wasn't it, they were  _part_  of John, he was controlling them, he was, yes, fucking himself in a sense that definitely not metaphorical, thrusting into himself, rocking back and forth on his knees to get  _his_ tentacle deeper inside his own body. Sherlock swallowed. He was almost prepared to throw himself facedown on the floor and rut against the carpet when everything abruptly stopped. 

John - _now_ he was hard, undeniably so - had stopped moving, all of him had, except for the rise and fall of his chest, and slight trembling that Sherlock put down to arousal. He moved his tentacles away from his body, gingerly as if it took some effort (there was a slick, rather obscene sound when the last appendage left his anus). He even let go of Sherlock's hands. Sherlock rubbed at his wrists, unconsciously swiped at the wet streaks his cock had left on his stomach. He was just getting his bearings, was about to get up and go to John, but the doctor held up the hand that wasn't still holding his cock. 

  _Wait._

An extremely thin tentacle, the thinnest Sherlock had seen so far, curved over John's shoulder as he settled into a more stable position on his haunches. John had that determined, preparing-for-difficulty look again, and he watched the tendril closely (no eyes for Sherlock at the moment). It touched the head of his prick (he was holding himself steady with one hand), and the end of it poked at the slit. John grit his teeth as he held it like that, made it wriggle a little, widening the opening, before pushing the thing about an inch into his shaft.

"Stay - there -  _Sherlock_ ," he growled between deep gulps of air, when his flatmate gave a sudden lurch in shock. "It's bloody hard keeping it down as it is."

And so Sherlock froze, holding himself tense as John began to swear, just under his breath, as he moved the tentacle further in, in little pushes and pulls (like, Sherlock thought, very, very tiny fucks) till it had to be halfway down his penis. Maybe even more. He held it still there, and Sherlock shivered at the thought of what that must be like. His hand went to his own cock, just touching it (he didn't want to get off yet, but, God, it was tempting). He found himself making a sympathetic noise when John, keening softly, pulled the tentacle out of his cock with excruciating slowness.

When it was done, when he let himself relax again and shook the numbness out of the hand that had been busy with his cock, John bared his teeth at his flatmate in a grin taut with effort and arousal. "You wanted a show, Sherlock?"

"I wasn't expecting that." The detective shuffled over to him, tilted his face into the touch of the tentacles that greeted him with feather-light strokes across his cheek. 

"I counted on it. I can go on for hours on a good day. Um." John took on a sheepish look, strange on someone who'd just put on that display of surpassing and unusual lewdness. "I don't usually do everything all at once like that," he said, rather as though he was trying to win back some modesty. "In case you were thinking it."

"It's amazing you even leave your room." 

"Yes, well, I have to eat. And go to work. And things." John touched his flatmate's face with his fingers this time (slightly moist from his precome), and he kissed Sherlock hungrily, licking into his mouth, as one of his tentacles curled around the detective's cock. "And it’s more fun with a friend."

Sherlock tensed at the touch, back curled in a tight forward curve. For a brief moment as John paused for breath, he looked down, saw the tentacle coiling around his prick, covering it completely from the base of the shaft to its head. The tip of the thing was rubbing, pulsing against his glans, and that, and the inexorable image of John pushing a tentacle into his own cock that it conjured up had white sparks dancing in Sherlock's vision.   
  
"Wait," he panted, and it was hard to get the word out because John's hand was at the back of his head, pulling him back into the kiss. " _Wait_ ," he repeated, more urgently, lips brushing against his flatmate's, as the thing tightened, the coils shifting against his too-sensitive skin. "Too close - John, _please_  - I - too  _close_ \--"  
  
He broke off. To be absolutely honest, Sherlock wasn't even sure what he was asking anymore, because he had been  _too close_  for a while now, riding on the fine edge of hormones and heat and sensation, and given that, given the situation (sex with a man with tentacles, that was happening now, wasn't it?), he just might go mad if John  _stopped now_ , but he didn't want to finish yet. He wanted this to  _last_. And all of a sudden it didn't matter what he wanted because he was coming, hard, into the sheath John's tentacle formed around his cock, semen dribbling over and between the coils while John held him, stroked him through his climax, mumbling tender obscenities as Sherlock muffled his own sharp cries against the doctor's skin.   
  
"Still okay?" asked John, when Sherlock was done and leaning limply against him. He removed the tentacle (soiled) from Sherlock's prick, was laying another, thicker one around the small of his flatmate's back to move him into a more comfortable position.  
  
"I'll bite you if you keep asking that." Sherlock's tone was fierce, though he spoiled the effect by nestling his head against John's shoulder. His hand (it had been on John's chest) slid downward to his flatmate's hip, fingers flexing teasingly close to John's cock.  
  
John laughed huskily, kissed the top of Sherlock's head, nuzzling at the sweat-damp curls. "I take it that you're up for more, then."


	6. Chapter 6

Sherlock made an affirmative noise, moved his hand up John's thigh until his fingertips were just brushing the thatch of his pubic hair. John breathed deep, and briefly tightened his arm around Sherlock's shoulders.  
  
"Just a minute," he said, getting to his feet. Bereft of John's support, Sherlock slid down until he was lying on the floor in a loose curl of limbs. He watched as John took a tube of something from the top of his set of drawers, walked over to the bed, and sat on the edge of it facing Sherlock, legs spread open, giving him a good view of everything.   
  
Sherlock rolled over onto his stomach, the carpet prickly against his skin, and sighed, stretching like a cat.  
  
"If you think I'm going to do all the work again," said John as he squirted the tube's contents into the palm of his hand, "you've got another thing coming. Come over here."  
  
He slicked his cock with the stuff as Sherlock shoved himself off of the floor and went to stand between John's knees. A tentacle went to his waist, pulling him closer until his shins were pressed against the bed. Up close like that, John kissed his stomach, the soft skin of his inner thigh, and the head of his cock, tongue darting out to taste the traces of his ejaculate. Sherlock's hand went to the back of his flatmate's head then, and his grip tightened (though his fingers couldn't get much purchase in that military cut John still wore his hair in) as John mouthed at his shaft, lips working on the length of it. He gave a little shudder at the cold touch of John's hand (the one he'd used to prepare his cock) on his balls as the doctor fondled them, and he had to reach for John's shoulder for support when the cool, slick fingers traveled from there to his entrance.  
  
"Oh, good," said John as the top joint of his index finger slid easily up past the still-stretched ring of muscle. He pushed another fingertip in next to it, and Sherlock grit his teeth as he worked them all the way inside, making little scissoring motions as he went. "Christ, that's  _good_ ," he repeated, his mouth against the light line of hair that trailed downwards from his flatmate's navel. "I told you," he explained, crooking his fingers, making Sherlock grunt as they brushed his prostate, "these things don't feel much" - he demonstrated exactly which things he meant by stroking one thick tentacle down the length of Sherlock's hardening cock - "and it's different like this. God, you feel  _fantastic._ "  
  
"John." It was an impatient reprimand, and Sherlock punctuated it by striking the doctor's shoulder just lightly enough for the blow to fall short of being actually violent. This was, like the start of John's wank, maddeningly, appallingly  _ordinary_.   
  
"Easy now." John patted the side of Sherlock's thigh with his free hand. "We'll get there."  
  
He was apparently enjoying himself,  _feeling_  things, as he said. He took his time, fingering Sherlock with excruciating slowness, lips caressing Sherlock's cock and scrotum while never actually taking any part of him into his mouth, never providing quite enough stimulation, until Sherlock whined, high and plaintive, long fingers digging urgently into John's shoulders (he couldn't reach much further down the doctor's back without encountering the tentacles).  
  
In response to that, John sent a few spindly tentacles (five, thought Sherlock, or six, or seven, or ten, and then he gave up counting) around the back of Sherlock's thigh, and made them push the into his flatmate's arse, forming a ring around his fingers. Sherlock ground down on them - he wasn't quite as full as he wanted to be, but it was better than just those damnably wicked fingers - and he yelped when, instead of going deeper, they hooked around his sphincter and stretched him open.   
  
"You're not  _that_  big," he choked, as they went on pulling his entrance even wider after John removed his fingers.

John gave him a patronizing look ( _We'll see about that_ , it promised). "I think you know what to do," he said, leaning back, and easing himself just a little further onto the bed. His cock, erect and leaking and smeared with lubricant , jutted up from between his legs, and he patted the inside of his right thigh invitingly, just in case Sherlock hadn't gotten the message.  
  
Stiffly, dimly wondering what he looked like from behind with his arse held open like that, Sherlock clambered onto the bed, on his knees, shins lying against the outside of John's spread thighs. He lowered himself, slowly, until he felt the head of John's prick against his perineum. His hips twitched forward (John was going to have bruises on his shoulders, the way he was gripping them) and he groaned when John's cock grazed the edge of his obscenely open entrance.   
  
"Steady," said John, wrapping tentacles high around Sherlock's thighs, using them to align the consulting detective's arse with his cock. His hands were on Sherlock's sides, and Sherlock loosened the vise grip he had on John's shoulders, transferred his hold to his flatmate's upper arms. "Steady, Sherlock."  
  
"Oh, fuck that!" Sherlock snapped, imperious and demanding and desperate.   
  
"Yeah, that's the idea, thanks." And John pulled his flatmate down and onto his cock. The heat of it as it pushed into his body past the tentacles was vastly different from the impassive touch and temperature of the appendages. It felt less surreal, more human, and _good_ , unbelievably good, even when Sherlock had to squirm to bring more of John  _in_. "Don't force it," the doctor gasped, and he wiggled the little tentacles a bit deeper into Sherlock's arse, made them stretch it a little wider. "Oh God - _fuck_ \- try to relax, you're so damn tight."  
  
Sherlock whimpered in reply. He'd meant to say something scathing about the improbability of being able to relax when your arse was being held open by other-dimensional tentacles, but it was lost when John ran a hand down his spine and he sank about half an inch further down his cock.   
  
"Not that that's a bad thing," amended John breathily, kissing Sherlock's chest. "Not a bad thing - at - all." His hips thrust upwards just as Sherlock pushed down, driving his cock all the way into Sherlock's body.   
  
Sherlock melted against him then, body pressed to John's, face buried at the corner of neck and shoulder. John had his arms around him, hands spread wide against his back, and he made a delicious little noise at the back of his throat when Sherlock rocked forward.  _Yes_ , he thought, glorying in the sensation of John moving inside him, the deep breaths John was taking that he could feel against his skin. And when the tentacles moved in a little deeper, a tiny, treacherous part of his brain thought,  _More._


	7. Chapter 7

**Notes for the Chapter:**

> *throws this down* Why, yes, it is taking me very long, but I really do intend to finish all the fic.

Sherlock tried an experimental bounce, making John give a most satisfying moan. He filed that as _successful,_ and did it again, this time noticing how the tentacles went ever so slightly slack. It occurred to him then that it probably took John a considerable effort to control them, rather more than it took to, say, curl his fingers around the base of Sherlock’s penis, like he was doing now - a logical conclusion, given that he’d said the appendages didn’t _feel_ much. He stored that information for future consideration, and, for the present, settled into a halting rhythm, pausing every now and then to adjust his position on John’s lap, to let John’s appendages shift and settle on and around different places on his body, to _breathe._ John, head thrown back with his hand and one tentacle loosely curled around Sherlock’s shaft, could hardly say he was doing all the work now.

“ _Perfect_ ,” he groaned, drawing a mass of other-worldly coils down Sherlock’s chest. “God, you’re a fucking genius, but let me - just let me--”

“Yes,” breathed Sherlock, fingers cupping John’s face as he leaned in for an eager, artless kiss. He was, he told himself, ready for anything, glorying in the other man’s inexplicable, extraordinary strangeness and solid familiarity.

 "More?" John asked, his voice almost breaking on the word.

For a moment, Sherlock wondered if he'd said the word aloud earlier, the line between thought and action blurred by all the rather alarming sex. He might have. But it was immaterial because John was indeed offering _more_ and he was more than willing to take it. He suspected he knew what John wanted, was certain of it when John slid his fingers down and back, touching the place where they were connected, but it was still a bit of a shock when the tip of a tentacle joined those fingers and pushed _in_.

Sherlock gasped sharply. He’d had one of those things inside him a scant few minutes ago ( _Had it really been just a few minutes? It already felt like a small eternity_ ), he already had data on what it felt like, how it moved - no, correction, how _John_ moved _it_ \- and he was quite capable of extrapolating what it would feel like beside John’s cock well enough to inure himself against any actual surprise. Or, rather, he would have been capable of it if he were in full possession of all his faculties instead of being caught up in the reality of being fucked by John Watson and all parts thereof. It was conceivable that he still might have managed it if John hadn’t used a devastating combination of his fingers and those spindly tentacles still holding Sherlock open to fractionally increase the pressure, slowly, gently, until he could let a second, slimmer appendage slither into his body.

“ _Fuck_.” John had one hand planted beside him on the bed, using it for support as he moved his hips in short, abbreviated thrusts. “You’re gorgeous, you are, fucking amazing, so fucking brilliant--”

Sherlock tried to respond in kind, he wanted to move, wanted to tell John exactly and in detail exactly what he was doing to him, but the instructions from his brain were moving across his synapses as though they were mired in treacle. All he could do was sit on John’s lap, clinging to his arms, making inarticulate moans and little breathless noises, utterly lost in the sensation of being so _full_ , stretched around the hard, hot length of John’s cock and the two tentacles sliding against it inside him. So lost, in fact, that he didn’t realize what the repositioning of John’s hands and other limbs meant until the actual motion was over and he was on the bed, on his back, with John on top of him.   

**Notes for the Chapter:**

> So, um, if you'd like me to write you a thing (weird or otherwise), and are interested in helping good, progressive causes, _and_ restoring my faith in humanity, you should know that I've signed up for [Fandom Trumps Hate](http://fandomtrumpshate.tumblr.com/), where fanworks are auctioned off in return for donations to a number of charities and the like. [This is my contributor page](https://jamesphillimoresumbrella.tumblr.com/post/155654882071/tepidspongebath-fth-contributor-page) and there are [so many other creators](https://fandomtrumpshateofferings.tumblr.com/) offering their works as well. Please check it out!


	8. Chapter 8

The change in position was everything. If he’d been lost to sensation before, it was nothing to what it was like now that he no longer had to worry about staying even somewhat upright and was therefore free to _observe_. Sherlock was suddenly more aware of precisely how the flared head of John’s cock was dragging against his inner walls, how the tentacles were probing, twisting next to it, making him feel impossibly tight, setting off sparks beneath his skin. And he could spread his legs wider like this, which was excellent because John was between them, pressed into and against him, pressing messy kisses onto his neck. Through all this, Sherlock was pleasantly aware of his own arousal ( _unusually short refractory period, interesting, investigate later_ ) until it was brought into sharp relief when the tentacle around his prick tightened roughly.

It was quite different from the gentler attention that John had lavished on that part of his anatomy after his first orgasm. Too different. A bit too much, with everything else. Sherlock tried to bite back a distressed shout and failed.

“You okay?” asked John, the words hot and damp against Sherlock’s skin.

Sherlock’s first attempt at a reply was lost in a soft cry as John’s hips bucked forward: he had more leverage like this, and it would have been glorious if Sherlock hadn’t been about to lose his mind. He swallowed thickly and managed to croak, “Need a minute.”

“Oh, Jesus.” John sounded genuinely alarmed. He began to withdraw his appendages, pulling them back tightly behind his shoulders, wincing when he heard the sound Sherlock made when the tentacles - all of them - slid out of his arse. “We can - we can stop if you want to. Sorry, Christ, I got carried away--”

“ _Just_ a minute.” Sherlock cut him off, dug his fingers into John’s hip to keep him from pulling out as well. Words were easier now, but that wasn’t necessarily what he wanted. “ _Only_ a minute, maybe not even that. Do I have to repeat myself?” He sighed gustily when John merely continued to look worried and nonplussed. “’Do whatever you like, whatever you can’, remember? I still want that.” Sherlock's hand slid up from the relatively safe region of John’s arse to where the tentacles began, and he kept it there, letting the things slip-slide over his fingers, up his arm. "I just need time to process the data."

“Data!” huffed John, and he had to bury his face against Sherlock’s shoulder to stifle a relieved laugh. “Only you would - you’re impossible, you know that?”

“You’re one to talk.” What was impossible was sounding even slightly irate as John moved in to kiss him as he spoke. His lips were moving against John’s before he got to the end of the sentence, and he pulled him closer, one hand on the back of his neck and the other buried amongst the tentacles on his back.

They moved beneath his palm, between his fingers, which he’d expected, but the _way_ they moved - the things pulsed and dilated, snaked and writhed, and Sherlock was certain he felt one split apart, branching off into thinner appendages that curled intimately around his forearm. For a moment, when John stopped kissing him long enough to draw a breath, Sherlock wondered what it would be like to press his chest against John’s back. He’d have to close his eyes, might even have to wear a blindfold, but, good God, it would be worth it. There was just time enough to speculate on whether or not John would allow it, before John’s mouth was on his, John was rolling his hips, moving gently, cautiously inside Sherlock, as his tentacles inched gently, cautiously across his skin. 

 

**Notes for the Chapter:**

> Inching along at ~600 words at a time. May I just say how delighted I am that there is a consentacles tag now? I don't think that was there when I started this, and I love it. Consent is sexy.


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